#include<iostream>
#include<cstdio>
int main()
{
    //向标准输出里面进行打印  stdout,cin->1
    std::cout<<"hello world"<<std::endl;
    printf("hello world\n");

    //向标准错误里面打印，stderr,cerr->2
    std::cerr<<"hello cerr"<<std::endl;
    fprintf(stderr,"hello stderr\n");
    return 0;
}
